Intermediate Bus Architecture (IBA) power systems are well known systems for distributing power. An example Intermediate Bus Architecture system 100 is illustrated in FIG. 1. By way of example, the system shown in FIG. 1 is a pure DC system, and accordingly no AC/DC converters are included in the system.
In such power systems the Intermediate Bus Converter (IBC) 101 delivers a pre-determined voltage to the Point of Load (POL) regulators 102-104 connected to the loads (not shown).
The Intermediate Bus Converter 101 could be one of three general types, namely fixed-ratio DC/DC converter (isolated or non-isolated), line regulated DC/DC converter or fully regulated DC/DC converter. The Intermediate Bus Converter receives an input voltage Vin which is typically a DC voltage in one of the ranges of 36-75 V, 18-36 V or 18-60 V.
The Intermediate Bus Converter outputs an Intermediate Bus Voltage (VIB) which is used as the input voltage to the Point of Load regulators.
The Point of Load regulators supply the loads in the user system. These Point of Loads are typically non-isolated. It is typical that the Intermediate Bus Converter's and Point of Load Regulators' topology can be any type, namely Buck, Boost, Buck-Boost, etc. isolated or unisolated.
In such a system, the Intermediate Bus Voltage is normally fixed, but with the emerging market of digitally managed Intermediate Bus Converters and Point of Load Regulators there is now a possibility to adjust the Intermediate Bus Voltage to achieve greater efficiencies.
It is also possible to have current sharing between Intermediate Bus Converters and also between Point of Load Regulators. This is achieved using multiple Intermediate Bus Converters and multiple Point of Load Regulators. Information is traded between the different power converters (in the same stage) using Current Sharing Busses (CSBs). There is typically only one such bus in the Intermediate Bus Converter stage. However, in the Point of Load Regulator stage, there can be numerous busses. The Current Sharing Busses are not a part of the invention disclosed herein, but it should be noted that the invention is not conditioned by the presence of Current Sharing Busses.
In a traditional Intermediate Bus Architecture system, the Intermediate Bus Voltage is not regulated for an optimized system efficiency based on the actual load conditions. Instead, the Intermediate Bus Voltage remains fixed independently of the output load.
In order to enable to newer power systems to vary the Intermediate Bus Voltage, it is necessary to include a Board Power Manager (BPM) 110, as shown in FIG. 1. The Board Power Manager accepts measurements from each of the Point of Load Regulators about their respective operating conditions e.g., output current and output voltage, and calculates based on these measurements, the appropriate Intermediate Bus Voltage. The Board Power Manager 110 then instructs the Intermediate Bus Converter, via a Power Management Bus, to either raise or lower its output voltage, and hence raise or lower the Intermediate Bus Voltage, for maximised efficiency.
However, this scheme suffers from a number of problems. For example, it is necessary to have a Board Power Manager that has been programmed with an algorithm that controls the output voltage by communication to the Intermediate Bus Converter. This Board Power Manager adds to the purchase cost of the system, and also adds to maintenance requirements of the system. In addition, the Board Power Manager 110 makes the system more complex since the Board Power Manager needs to collect data from the Point of Load Regulators before adjusting the output voltage from the Intermediate Bus Converter.
In view of the problems in known dynamic Intermediate Bus Voltage power systems, it would be desirable to provide an apparatus and method for controlling the Intermediate Bus Voltage so as to simplify maintenance and operation of the power system whilst still providing maximal power efficiency.